iStock/Thinkstock(CHARLESTON, S.C.) — Former police officer Michael Slager, who is accused of murdering an unarmed black man, takes the stand in his own defense at his murder trial Tuesday morning.

Slager, who is white, is accused of killing Walter Scott at a traffic stop on April 4, 2015, in North Charleston, South Carolina, when Slager was an officer for the city’s police department.

Witness video that surfaced shortly after the deadly encounter appears to show the moment Slager fatally shot Scott as he ran away. The video garnered national attention, propelling Slager into the spotlight.

Feidin Santana, who filmed the video, was called to testify by the prosecution earlier this month, during which he recounted the moments before, during and after he witnessed the deadly shooting. Santana told the court he saw an officer chasing Scott, heard an “electric sound” — later determined to be a Taser and saw the officer punch the man once the man was on the ground.

He said the black man tried to get away from the Taser and said the officer, who Santana identified in court as Slager, was on top of the man who he later learned was Scott.

He said Slager was holding onto Scott but Scott was able to get away.

“After he got away … [the officer] shoot the man running from him,” Santana said. “And he shoot until he gets on the ground.”

Slager, 34, has pleaded not guilty to murder. Slager’s attorneys have said the witness video doesn’t show the whole struggle between Slager and Scott and does not give the perspective of events from Slager’s point of view.